1. Field of the Invention
The present invention relates to an improved pulse radar system which may for example be mounted on a vehicle to detect targets existing in the direction of movement of the vehicle and which may be particularly useful in applications where a plurality of paths are provided for the reflected waves from the target.
2. Description of the Prior Art
Pulse radar systems for detecting the relative distance to targets are known in the art in which the radar signals consisting of high frequency pulsed signals are transmitted against a target so that the echo pulse received in response to the sending of each radar pulse is integrated to remove the noise component and the resulting signal is considered as the reflected signal from the target to obtain the required distance information in accordance with the time delay between the transmission and the reception of the pulse. However, if such pulse radar system is mounted on a vehicle, for example, in addition to the reflected pulses from a target which are directly returned to the radar receiver, there are many echo pulses which are rereflected from the ground or other targets and indirectly returned to the radar receiver and therefore the sum effect (hereinafter referred to as a multipath effect) of these pulses tends to cancel the inputs to the receiver despite the presence of the target. For this reason, a method of processing signals through a simple integration as used in the conventional pulse radar system has the danger of generating an erroneous output signal indicating the non-existence of target despite the actual presence of the target when the absence of received signals due to the multipath effect lasts over a relatively long period of time. This means that where such pulse radar system is used as an auxiliary device for safe driving of a vehicle during the night or in the fog rain, the use of the pulse radar system tends to expose the driver to danger despite its intended purpose of fail safe.